Beyond Megapixels 438
TheTechLounge points to this "first of a three-part series of editorial articles examining current digital photography hardware, as well as the author's views of what is to come." It boils down to the excellent point that pixel count alone is not the way to evaluate digital camera capabilities.
The Megapixel illusion (Score:3, Informative)
With digicams, megapixels only matter (these days) for large prints, especially since most monitors these days are used at 1024x768, which is ... 768 kPixels :).
How about using SNR ? I know it's difficult to compute, but reviewers could use VHQ analog film, film-scan it and compare the output to digital output.
For me, its the optical zoom ability (Score:5, Informative)
For example, this picture I took with my decent megapixel digital camera, my first time using it [utulsa.edu] was a terrible disappointment because it was a great shot ruined just based on my not having the proper optical zoom capabilities.
(And my mistake in buying a camera that I thought would be top of the line, and stupidly didn't notice the difference between digital and optical zoom, this being my first move off of traditional cameras.)
the results you aren't pleased with.. (Score:3, Informative)
although most cameras are purchased prior to an impending expected use, is it fair to blame a camera the first time you used it? most photogs know they need to use a camera for a while before they can expect the best the camera can produce.
1 mp camera on Spirit (Score:5, Informative)
From the article: "NASA's Spirit Rover is providing a lesson to aspiring digital photographers: Spend your money on the lens, not the pixels. Anyone who has ever agonized over whether to buy a 3-megapixel or 4-megapixel digital camera might be surprised to learn that Spirit's stunningly detailed images of Mars are made with a 1-megapixel model, a palm-sized 9-ounce marvel that would be coveted in any geek's shirt pocket. Spirit's images are IMAX quality, mission managers say. "
Sigma SD10 (Score:5, Informative)
Here's a comprehensive review [dpreview.com] of Sigma's camera.
Re:It always... (Score:2, Informative)
Additive vs. subtractive color (Score:3, Informative)
Article... (Score:2, Informative)
Re:For me, its the optical zoom ability (Score:4, Informative)
Re:something I don't understand (Score:3, Informative)
Well, some of the more specialist photo printers that contain more than five colours of ink do now include a greenish shade of ink. The main reason though is that most hues of light can be simulated by mixing varying intensities of red, green and blue. This is an additive model where 100% of red, green and blue is white.
For prints however, a subtractive model is used - what you are actually seeing when you look at a print is a the light being reflected from it. You generally start with a white background and the cyan, magenta and yellow pigments block certain hues in the reflection. 100% saturation of all three pigments creates black (in theory at least), which is perceived as an absence of colour.
The Digital Dark Age (Score:2, Informative)
Re:It always... (Score:4, Informative)
Once an aliased image is captured by the CCD, no amount of image processing can remove the artifacts. That is why high end digital cameras like the Nikon D1 contain an optical low-pass filter between the lens and the CCD that purposefully degrades the quality of the lens assembly.
spatial resolution vs. temporal resolution (Score:4, Informative)
I've done experiments with my 3MP camera, taking multiple shots from the same angle and layering them in photoshop. The enhanced resolution can be downright breathtaking, but the practice is only practical for still lifes and landscapes. What are you going to do with that 1MP camera when you want a high resolution image of janie's first smile?
Obvious (Score:5, Informative)
A bad lens will produce a bad image regardless of the image sensor. Sometimes an image sensor will not have enough resolution to detect the distortion due to chromatic and spherical aberrations. But when the same manufacturer slaps a new sensor on last year's lens, the new sensor can pick up better on the aberration and the pictures end up looking lousy.
Another feature to bear in mind is hardware {optical} zoom. Don't buy a camera without it and don't reject a camera for not having software {digital} zoom -- your favourite graphics editor can do this for you.
Cheap image sensors are invariably noisy. Big pixels can hold more initial charge, therefore can accept more light in the course of an exposure. The sensor will only be saturated in really bright light, and the amount of charge remaining on the pixel {which is a measure of how much light didn't hit it} can be measured more accurately: one "unit" on the ubiquitous 0-255 scale represents many electrons. But more silicon costs more money. Small pixels don't have the same capacitance, so can't accept as much light before becoming saturated -- you have to run a shorter exposure. And the number of electrons per ADC count is smaller. The net result of having a higher density in the image sensor is that even in bright light, the resulting pictures will look a little bit as though they were taken in poor light. Of course, you can remove the noise by downsampling, but then you lose the benefit of the higher-res sensor.
And what's with the confusing term "digital SLR" ? As far as I can see, all digital cameras with LCD viewfinders are by definition SLRs, since the same lens is used for viewing and taking the picture.
Re:1 mp camera on Spirit (Score:4, Informative)
The lens is nice, and being fixed-focus and fixed-zoom helps with the quality over a consumer-grade camera, but the tripod is more important.
Re:For me, its the optical zoom ability (Score:2, Informative)
Olympus Camedia C-730 Ultra Zoom, 3MP, 10x optical zoom
Hewlet Packard Photosmart 850, 4MP, 8x optical
Nikon Coolpix 5700, 5MP, 8x optical zoom
Panasonic Lumix FZ-1, 2MP, 12x optical zoom(!)
Olympus C-8080 WZ, 8MP, 5x optical zoom
Re:It always... (Score:2, Informative)
The larger sensors do way better in lower light which allows for a wider range of f stops and shutter speeds without getting a shitty, noisy image.
Re:It always... (Score:5, Informative)
A smaller sensor is more noisy and more prone to chromatic abberation. Which is why my old EOS D30 with a large 3MP CMOS sensor produces better pictures than Sony's F828, which crams 8MP onto a tiny CCD. 3MP prints great up to 9x6" and is uable at 12x8". It's difficult to get a good print off a CCD camera above 7x5". Larger images don't need to be distorted as much by the lens to be focussed down onto a larger sensor, and that matters. More photons per unit area matters for faithful colour reproduction.
But like another poster said, most of these images are destined to be viewed only on screen, so most of the resolution is wasted. About the only thing it's useful for is giving the freedom to crop.
Re:Dynamic Range and the SIZE of the CCD!! (Score:2, Informative)
Good optics depends on
quality of the optics
diameter of the lens (larger the better)
the last depends on the size of the camera. bigger the camera, larger the lens can be (but not always necessarily). There is a size limit for a film camera due to the film size. you cant make a tiny pocket film camera.
But a digicam can be made smaller as the sensor is tiny. Smaller the camera, worse its optics. And so is its purple fringing.
optical resolution is far more important (Score:3, Informative)
The article fails to address the issue of optical resolution, i.e. lens quality and aperture. Does the number of pixels act as the resolution limiter, or does the quality or size of the lens limit resolution? Many consumer cameras use poor quality small lenses, but boast of large numbers of pixels. Since CCDs are cheap and good lenses aren't, why not over sample the image enough so the consumer thinks they're getting a superior image, and has to pay more for flash memory? The number of pixels can be irrelevant for a camera with a small or cheap lens. Larger aperture lenses will always resolve better, as is the case with all imaging optics anywhere in the spectrum between telescopes and microscopes. Cameras are no different.
The reason professional cameras are better is not just because the CCD is larger. A larger CCD demands a larger lens. That is the difference.
Furthermore, sensitivity and CCD size may not matter at all! The problem of noise for smaller pixels is only relevant when the camera is capturing lower intensity images. Brighter intensities overcome the noise. Larger aperture lenses also collect more light and resolve better, reducing noise and increasing contrast.
What's even more important than pixels? (Score:3, Informative)
- The quality of the body and mechanicals. No point in getting a nice digicam or DSLR when it's going to break in six months/5,000 images.
- The camera's firmware. Canon Digital Rebel owners know what I'm talking about. While firmware won't make or break a camera it CAN have a big impact. If the camera doesn't let you do what you need to do, all the glass and megapixels won't mean poop.
- Many others have mentioned this: egronomics. If you're spending time trying to find the button that lets you do what you need to do then you've missed the shot.
- Control over the camera. I think this is actually a bigger deal than megapixels or glass. If you don't have the control over the camera that you need, then everything else doesn't matter. This is more of a prosumer concern than a "I just wanna take some pictures"-consumer. However, it does matter. That's why SLR's are popular - people want control.
Re:It always... (Score:2, Informative)
No! :-)
But that is exactly right.
Sure it is, that's why rain comes in drops instead of sheets. Not that this has anything to do with the discussion.
Lenses can condense light or spread it out. This is called magnification and has nothing to do with focus. But again, this is of no consequence to the matter at hand.
There is a finite amount of light passing through a lens and hitting the CCD array. One can increase the number of sensors without increasing the physical dimensions of the array by making the sensors smaller. Since the size of the array is unchanged, the amount of light hitting it is unchanged. Since there are more sensors and the same amount of light, there is less light per sensor.
Some high end systems use a physically larger array to increase the number of sensors without decreasing the amount of light per sensor. This is analagous to using large film formats in order to capture images with greater detail.
The downside to bigger chips is that they are more expensive to manufacture.
Re:For me, its the optical zoom ability (Score:5, Informative)
The shutter was open for 1/8 second. Usually the most stable hands can only hold a camera still for 1/focal length. ie, for a standard camera you shouldn't shoot any slower than 1/30 of a second.
Having a longer focal length would have exacerbated the problem. What you need here is a greater light sensitivity (higher ISO). A higher ISO would have allowed you to shoot with a faster shutter speed.
I would suggest reading up a bit at www.dpreview.com [dpreview.com] or www.steves-digicams.com [steves-digicams.com] before buying a new camera.
If you want to see my credentials for making this comment take a look at: http://www.pbase.com/efatapo [pbase.com]
Re:But MP matters for size! (Score:1, Informative)
Re:Why were MP ever such a big deal? (Score:3, Informative)
compare the physical size of a 640x480 image on your screen to the physical size of a standard print.
If I want a good picture for viewing on monitor I want it to be at least that big (probably bigger since it's easy to make it smaller if needed but you can't make it larger (without loosing quality)).
granted. i don't want to have to resize an image to look at it quickly. i suppose that thumbnail viewers are the obvious answer, though, to me, a photograph is a photograph. for the majority of pictures, a "small" image (640x480) is more than large enough for me. hence my comment regarding taking pictures of blueprints. there are situations where a high resolution would come in handy, but for the majority of photographs, 3200x2400 is insane unless you are making huge prints (and even then, you can't get much bigger than letter-size with acceptable quality).
and why would you say that you'll use 35mm for prints? it makes no sense, if the digital camera can give the same results...
the digital camera cannot give the same results. 3200x2400 (~8MP) at 300dpi is only ~8" x ~10.5" -- a digital camera is not as versatile as film if i want this image blown up to something along the size of 3' x 5'.
as the other poster said, his 2.2MP camera is only good enough for prints up to around 5" x 7" -- anything larger than that is going to look pretty crappy.
-mike
larger sensor = better S/N (Score:5, Informative)
Well, it's fact. The larger the surface area of each cell, the better signal to noise ratio you will get. CMOS yields better quality than CCD, as well- although the margin has dropped as CCD sensors and the electronics behind them have improved faster(due to everyone and their grandmother working with CCDR sensors) than CMOS.
This phenomenon can be seen clearly in both the non-CMOS 14 megapixel Kodak 14n, or the Sony F828, which has a VERY tiny 8 megapixel CCD sensor. Both are horrendously noisy at their lowest ISO settings.
My Canon 10D has better noise characteristics at about 400 ISO than my Canon G1 had at 50 ISO, and 400 is about the limit I feel is appropriate for an 8x10. For images resized to 800x600 for, say, large images linked off a website, ISO 800 or 1600 still yields pretty decent images. The example he gives of buckets of water is flawed, since falling rain isn't *focused* like light is. Light entering a lens is just being focused on a smaller area. Sure the area is smaller, but it's also brighter.
Light is focused, but it's also made up of particles. Further, the smaller the sensor, the smaller the lens. The smaller the lens, the less light is gathered.
Smaller sensors also require much more precise optics and focusing systems(or smaller apertures, limiting light input even further). Tiny sensors are also very prone to flare.
Re:Obvious (Score:2, Informative)
Re:I'm ambivalent (Score:3, Informative)
Example: Canon's EOS Rebel Digital is $1,000 with a simple lens. It uses the same 6.2 megapixel sensor as the higher-end EOS 10D. It's a true SLR-style camera, with the same EOS lens mount. But it lacks some of the features that the ~$1,500 EOS 10D does. The rebel digital has a partially plastic instead of totally metal body, lower amount of frames capturable in burst mode, etc.
And thus we arrive to the "Prosumer" wording. A simple professional (a wedding photographer, as someone else mentioned, or a photography student who needs digital) could use this camera without hurting too much for some of the missing features. In reality, though, many camera companies realize that a bigger market is consumers who are wealthy gadget geeks and could justify the $1,000 of the camera as compared to the higher-end consumer models, but not the $1,500 of the 10D.
For alternate examples, see Photoshop LE ($100, and lacking the features that most semi-skilled PS users don't touch anyway), or mid-range to high-end triple-CCD DV cameras (occasionally used in Hollywood, but only for specific reasons, but heavily used by local video production houses and the occasional wealthy camera geek).
I would challenge you to come up with a single word, already in common circulation in the English language, that could effectively say, "hey, this is not quite as good as that really high-end equipment, but it's definitely much better than that stuff over there". Also, remeber that for marketing reasons this word needs to carry no real negative connotation.
Re:The Megapixel illusion (Score:3, Informative)
I would be very happy if camera vendors and review sites started prominently listing sensor surface area as prominent figure of merit.
One, any camera supporting EXIF will likely include sensor dimension information in every photograph. Two, looking at the stats listed on www.dpreview.com, this sort of information is readily accessible. Just because c|net doesn't list it for the point'n'shop consumers, doesn't mean you can't make YOUR purchasing decision with that information.
Re:Why were MP ever such a big deal? (Score:1, Informative)
They are fantastic cameras. The new mju-300 and mju-400 digitals are good as well.
Oddly, there is still a delay difference (Score:2, Informative)
Not one that I notice, but apparently there's enough of a difference between a film and digital SLR to give Sports Illustrated photographers trouble:
You can read the whole article at http://www.robgalbraith.com/bins/multi_page.asp?ci d=7-6453-6821 [robgalbraith.com].
Five facts from a professional photographer (Score:5, Informative)
1. Image quality will be determined by the combination of how many pixels you capture (megapixel count/resolution) and the size of those pixels (sensor size/photosite size), with the weight of the influence going to the photosite size. Thus, resolution being equal between two cameras, the camera with the larger sensor size will give you higher quality captures.
2. Garbage In, Garbage Out applies to cameras too. This should be obvious. Make sure your lens is able to capture all the data you want to feed to your sensor. If you have a full-frame, 24x36mm 11mp Canon 1Ds (the current professional favorite, myself included), you are wasting it's resolution by putting a cheap lens on it. I've noticed, in fact, that even the highest-quality lenses tend to be unable to deliver enough detail to this stunning sensor, so a cheapo lens is going to f*ck you.
3. For professional use, film is now dead. Game over. I've done the head-to-head comparisons. I own medium and large-format cameras. I own a high-end drumscanner. I own a large-format printer. I've compared the quality from my previous breadwinning equipment (medium format film scanned by drumscanner) to my current breadwinning equipment (full-frame digital Canon 1Ds) and the digital kicks film ass. That's why it's my current breadwinner.
Seriously, I had 4x6 foot prints made (notice I said FEET, not INCHES) from drum-scanned 6x7cm transparencies, and from 11mp Canon 1Ds captures, and my own lab couldn't tell the difference. Bye-bye film. And the $10,000 price tag was paid for in film/processing savings before I even got the credit card bill. (for more about how cost affects quality, see below, #5)
4. The best camera for you is all about what you intend to do with it. A camera is just a tool. Pick the right one for the job. Because of this, most professionals have, on average, more than 3 different camera systems. So, decide what you want the camera for, and the rest of the decisions about it's suitability get easy.
The most important factor is usually not sheer resolution and image quality. It's about usability of design and ease of handling. If it were all about resolution then most photographers would be using 8x10-inch view cameras. But we realize that a stunning, mega-high-resolution image is useless if the important moment we wanted to capture was missed due to slow camera operation.
That's why most pros use medium format or 35mm, and most ams use point'n'shoots.
So, pick a camera that feels good, is understandable to operate, and doesn't get in your way. After these criteria are satisfied THEN you look at resolution/sensor size.
5. The single most important equation for making better photographs is (forethought x volume of action). In other words, think about what you want to achieve with your images, then shoot as much as you can, and hone your results. This is really where digital capture shifts paradigms. Once you go digital, ANY digital, your visual experiments cost you nothing.
With film, every time you want to try something new, you are still paying for film and processing (even if you own your own darkroom). This means, effectively, that film and processing are an economic tax on your creative growth.
So, as long as you stay focused on what you want to achieve (rather then just shooting because you can), buying ANY decent digital camera will yield you better results then sticking with film, and it's use tax.
Class dismissed.
Re:Snap (Score:3, Informative)
It's still not the same - particularly with the lower end digital SLRs.
While the single-picture lag may not be so great, the key number is buffer size. The 300D, for example has a buffer size of 3 images. That means you can take 3 pictures but then have to wait several seconds while those are saved onto your CF card before being able to shoot again. Definitely not the same as film for action shots.
Re:Why were MP ever such a big deal? (Score:3, Informative)
More then speed is price per picture... When I go to a wedding with a digital camera, I usually end up with hundreds of 4MP pictures. I couldn't do that if I was buying film and paying for processing and developing for 12-15 copies of the top 20-30 pictures to send out to the family when they keep one or two pictures.
With digital, I can take hundreds easily, public the best 20-50 pictures online and people can tell me which ones they want.
Re:Why were MP ever such a big deal? (Score:5, Informative)
yep. they basically sold 35mm movie film in 24 frame strips. movie film doesn't have the same high quality requirements as still photography film because any problem in a frame is corrected 1/24th of a second later.
movie film is therefore much much cheaper per frame than good photographic film. so they were making out like bandits when they hooked someone. and because it doesn't use e-6/c-41 chemicals you had to get it developed either at a motion film lab (not likely) or with them.
btw, movie film also has a really short shelf life unless kept in special volts at exact temperatures. this is true even AFTER the film is developed!
seattle filmworks was one a very nasty scam for several decades. a few years ago they finally switched to (really crappy) c-41 film.
Professional Printers.... (Score:2, Informative)
Not to be a troll... but professional prints never come from a laser printer...and they cost lots more than 10,000
"professional" Digital prints are usualy created with a digital minilab (such as a Noritsu or Fuji) that can also process film. These machines can print 4x6's for less than 5 cents, and 8x10s for less than 20 cents... Of course a high volume digital minilab also costs 150-200K.
However these traditional "wet" printers are going to phase out within the next 5 years or so as inkjet technology continues to advance. Noritsu and Epson already have there own "Dry" (i.e. inkjet) digital minilabs. Even Kodak and HP worked together to create a Inkjet digital minilab under the name of Phogenix... however they abondoned the project so they could each pursue individual solutions.
The artical does make some good points... resolution isent everything. This isent realy a new arguement...some film photogrophters would obsess over the best film to use... Fuji provia 100 has long been regarded as one of the best 35mm films becasue of is ability to retain more detail, with less grain. Of course if you use nice film with a cheep glass... you still get a cheep looking photo.
Re:sony f707 (Score:3, Informative)
Also, if you get a non-canon flash, get the Sigma not the sunpak, I purchased the Sunpak power zoom 40x, and while it works well for snapshots the Sigma is much more flexible (and only a little more expensive).
Re:It always... (Score:5, Informative)
This depends on the shape of the CCD active areas that are used to capture photons. In the "worst case" where the receptors are essentially discrete points on a grid, an optical blur is needed so photons that would otherwise land in between the sensors have a chance to be captured. In practice, I would guess that the sensors cover about 50% of the usable area, so the remaining 50% must be made up with low-pass filtering to avoid aliasing. (Think of filming headlights; if they're in focus they'll be two discrete points of light, but as you defocus the lights will expand until they overlap.)
A similar problem also comes up in motion video; the aperture is typically open 75% of the time, then closed 25% while the film advances. This results in motion aliasing such as helicopter blades and wagon wheels spinning backwards, etc. Digital video may be able to substantially reduce this problem, but ironically most people have grown accustomed to it, to the point where non-aliased video simply doesn't "look right."
The Foveon approach is a step in the right direction for image capture, since the Bayer interpolation from most other cameras is prone to all sorts of artifacts. Perhaps a camera could be built that would expose the same CCD array through red, green and blue filters in sequence, then apply software to compensate for slight motion between frames.
Similarly, imagine a camera that would expose the CCD for 1/10,000 of a second, then 1/1000, then 1/100, then 1/10, and combine the resulting frames into a single high-dynamic-range image. When the sun is millions of times brighter than the shadows, [0..255] simply isn't going to do justice.
In my opionion, the next few years of digital photography is going to be mighty interesting.
Re:Why were MP ever such a big deal? (Score:2, Informative)
Focal length multiplier, DOF, and ISO/CCD issues (Score:3, Informative)
1. Almost all DSLR's have what is called a focal length multiplier - tends to be 1.3 or 1.5/1.6. This means that your "normal" 28mm lens ends up being a 42mm lens (for 1.5x focal length multiplier) - this has to do with the fact that the CCD chip is not "full-size". This is great for tele shots - i.e. your 300mm lens becomes 450mm ... but really sucks for wide-angle used - i.e. you need a 18mm lens to get a 28mm shot. All point-n-shoot digicams show the 35mm "equivelent", but in actual fact, that is NOT their focal length.
2. Related to the above is Depth of Field - especially with point-n-shoots, your DOF is much longer, so if you want to shoot a picture that is "tack-sharp" on the subject, but have a blurred foreground/background, that is more difficult - although on the other hand, you do have more DOF if you want that.
3. Another issue somewhat touched upon briefly is differences in the CCD size between point-n-shoot and DLSR's. With all else equal, the small the size of the imaging pixels, the more noise that can be present, and this tends to go up dramatically if ISO is turned up (first thing I do on a point-n-shoot is turn OFF the auto-ISO and force is to the lowest setting). I'm sure some will disagree, but I'd challange you to print, say a 10X15 print from one of the 8MP digicams compared to a DLSR, both shot in GOOD light (with lowest ISO). Yea, under photoshop, that DSLR shot is just super-silky smooth, but on the 10X15 print, I bet you'd be hard pressed to tell the difference. Having said that, crank up the ISO in your point-n-shoot to say, 800 (yes, even in the newest digicams), and it will look like CRAP - again, at outlined, because the sensor sizes are so darn small, whereas on the DSLR's, you can get away with this (and increase your shutter speed so you don't get motion blur) and the picture may be decent, especially with noise-reducting software/filters applied. From reading Part 1, THIS is the real emphasis of the article.
I've only scratched the surface here - the article talks about a lot of the above, but most of the Slashdotter's seem to have blown right by this stuff.
Hulkster
P.S. On those Mars pictures, YES, they were done with a 1MP digicam (with BIG sensors), but just about everything folks have seen is stiched togather, so you are (in some cases), seeing like an "effective" 50+MP shot - welll DUHHH it looks so good!
Re:It always... (Score:2, Informative)
In any optical system, a 'normal' image perspective is achieved with a lens focal length equal to the diagonal measurement of the photosite. For 35mm film, this equates to 43mm. (24mm x 36mm)
As the size of the photosite diminishes, so does the focal length of the lens required to maintain a 'normal' perspective. so an 8mm x 12mm sensor would need a lens focal length of 14mm for a normal perspective.
Here comes the tricky part. the f/stop of the lens system is the ratio of the focal length to the area of the aperture opening of the lens. this is universal to any optical system, no matter the size of the photosite. f/16 in 35mm lets the same amount of light through as f/16 in 6cm x 9cm, aps, and any other format.
diffraction is an effect that causes distortion that increases as the physical size of the aperture decreases. Thus you get more diffraction induced distortion with a picture taken at f/16 on a 35mm camera than a picture taken at f/16 on a large format camera. This is a law of physics, there is no 'shortcut' around it.
The optimum aperture for minimum distortion from diffration and aberrations in 35mm is around f/8. A similar picture taken on a digital camera with a smaller sensor at f/8 would result in much more diffration induced distortion.
Since the f-stop required to make a properly exposed image doesn't change just because the size of the format changes, a smaller format photosite will always result in an image with less detail because of diffration, all else being equal.
Re:Why were MP ever such a big deal? (Score:2, Informative)
Re:Focal length multiplier, DOF, and ISO/CCD issue (Score:3, Informative)
The only way in which a 300mm lens is remotely like a 450mm lens when used with the smaller physical sensor is that they would deliver the same field of view. The problem is, a given lens produces a image whose sharpness is a fixed physical size (like .01mm) in the focal plane. The smallest point feature is blurred to this size at the film or sensor.
As a reductio ad absurdum which illustrates the issue, imagine a standard 35mm telephoto lens with 300mm maximum focal length, used with an ultra-tiny CCD sensor exactly .02mm across. The field of view present in the image is in fact equivalent to having a 360,000mm=3km lens -- I can see the bright red metallic print hawking this on the lens packaging now. Think of the stunning shots you can take of shy and endangered wildlife in the next state over from the comfort of your own porch! Sadly, thanks to the limits of the lens optics, such an image would contain only 4 independent blobs of color (completely independent of the number of pixels in which those blobs are captured).
In reality, since the cost drivers for lens design is performance "off axis" or away from the optical center, coupling a high-performance 35mm lens with a smaller sensor is wasting this off-axis performance: the maximum field angle is going to be smaller! This may however allow you to use cheaper 35mm lenses which would suffer from unacceptable aberrations at large field angles with digital cameras, since you're only using the "center of the glass".
Re:larger sensor = better S/N (Score:4, Informative)
A lens designed for a 35mm film camera will project a focused image onto the film plane. The image will be circular. The rectangle of the 35mm film frame that you are exposing will barely fit within the circle (i.e. the corners of the film frame will just be touching the edge of the circle).
On a dSLR, like the Nikon D70 (referenced in the article), the sensor is smaller than the film frame of the 35 mm camera, and as a result the sensor fits more easily into the boundaries of the image circle formed by the lens.
Because of this, the effective field of view changes. The area of the D70's sensor is roughly 2/3 that of a 35mm film frame. As a result, the D70's "crop factor", or its "focal length multiplier", is around 1.5x. Attach a 50mm lens to the D70 and the field of view captured by its sensor will be roughly equal to that which a 35mm camera would capture using a 75mm lens, because the D70 is only capturing a smaller area of the image.
Clearly, there is less light hitting the D70's sensor with the same lens / same aperature as compared to a 35mm film frame. However, the density of the light falling on the D70's sensor with the same lens at the same aperature is exactly the same as the light falling on the film in a 35mm camera. The difference is that the D70's sensor is gathering less of the lens's total image. Take a shot at f2.8 on the D70 set to ISO 200, and you should get the same exposure as the same shot at f2.8 on the 35mm camera with ISO 200 film, since the density of the light striking the sensor / film is the same in both cases.
What is most interesting is that lenses tend to produce more distortion toward the boundary of the image circle (i.e., at the corners of a 35mm photo). On the D70, using a normal 35mm lense, the image is captured from the center of the image circle, resulting in less distortion from the lens.
At the same time, Nikon has produced lenses specifically designed for the D70's sensor size. These lenses are smaller than the equivelant lens for a 35mm camera. The reason? These lenses only need to produce a smaller image circle than a 35mm lens, one that barely encompasses the sensor size of the D70 (and would not fully encompass the 35mm film frame). They are only capturing the light necessary to create an image circle of that size. Therefore, the outer edges of the lens elements that would be needed if the lens were made for a 35mm camera can be discarded, resulting in a smaller, lighter lens.
Larger photo sites do require more light than a smaller photo site to achieve the same exposure. But again, it is the density of the light that evens the playing field. A photoreceptor site of 4 nm^2 will gather 4 times the light of a 1 nm^2 photoreceptor site. Suppose a maximum of 250,000 photons are collected by the 1 nm^2 photoreceptor, and the 4 nm^2 site collects a maximum 1,000,000. Now, suppose with current technology I can accurately count the number of photons collected by a photoreceptor to within +/- 1000. Obviously, 1000 is a larger percentage of the 1 nm^2 photoreceptor's 250,000 capacity than it is for the 4 nm^2 receptor's 1,000,000 capacity - hence the 4 nm^2 receptor's accuracy is much greater than the 1 nm^2's.
In any case, don't take my word for this, I'm not a rocket scientist or anything. But these guys [space.com] are.
Re:Snap (Score:3, Informative)
My first test printing comparable images from drum-scanned film and directly from the 1Ds showed far better results at 24"x16" prints from the 1Ds--and then I realized I'd been shooting the 1Ds at ISO 400. My jaw dropped.
It turns out that the size of the scan stops being meaningful because of film grain, and that the amount of film grain turns out to make more of a difference in producing large prints than you'd expect from the "line pairs per inch" measurements. The grain just kills you trying to make enlargements, the cleanliness of the 1Ds image results in larger prints that come closer to very high-qulilty medium-format prints than 35mm.
I did a quick "review of the 1Ds for film photographers", it still needs some work, but you're welcome to read it. [rockslidephoto.com]
The price tag is large for the 1Ds. For me, that's not an issue, it pays for itself in reduced film and processing costs in a year or so--and I get better results--and I get better flexiblity.
To my eye, sensors have well surpassed color film. Black and white is going to be closer, but ... I don't think you should rely (if you are, I don't mean to put words in your mouth) on "megapixels" from film scans as being comparable to "megapixels" from digital sensors directly. Do the experiment, you might be surprised.
Bayer patterns are RGBG anyway (Score:3, Informative)
Some more advanced patterns use RGBY, where Y is munged Red and Green data- it's backed out in the sensor calculations.
The fastest (ISO rating) sensors use CMY (but I forget if its doubled M or doubled Y, or even if the last one is G for colour accuracy).
Ask yourself why- cyan is the opposite of red- how is cyan made? Magenta(R+B) and Yellow(R+G). Only the 'red' can pass thru, thus 1/2 the light is lost.
Sadly the matrix that is used to munge this data out of the wierd format is very odd looking and introduces colour errors (if the wavelenghts overlap certain peaks you are unable to determine which was which).
Printing, however, isn't the same as light. So you have to operate in the reverse- which means CMYK inks. Thats why you don't see green ink- the light has to be absorbed byt the inks, and therefore they have to be 'double' absorbed.
Lost ya yet?
Yes, I work for Kodak.
Re:Why were MP ever such a big deal? (Score:2, Informative)
And it's not just about the immediacy of the image (as you infer in a later comment). Digital makes an excellent teaching tool for a number of reasons. Not only can you check the image immediately, but you can dissect the image by looking at the EXIF information and learn about what works and why. What was the ISO setting, shutter speed and aperature setting on this really good image and what were they on one that's not so good of the same subject at the same time of day? What settings are giving me the DOF I want for a particular shot? You can also shoot as many pics as you want to capture the changing light (or changing subject matter with small kids or animals) without having to worry about what it's going to cost in terms of processing and film purchases.
Your statements regarding "the only reason" you'd do something simply highlights your limited experience with digital and your bias toward film. Saying you wouldn't use digital for a letter sized print without giving a single reason is pure prejudicial thinking.
Given my own experience in digital I'd have to conclude that you've either never done digital prints using decent capture and output devices or you simply don't know how to do it right. The fact of the matter is you can make excellent 8x10's even with a 3MP camera, good technique and a good printer.
Re:Five facts from a professional photographer (Score:2, Informative)
You can use 45 as a "bare minimum" if you like, but you're simply wasting resolution, unless you happen to be shooting Ansel-Adamsy forest pictures for a 10 foot print to be viewed 3 feet away.
My clients are primarily glossy fashion magazines, where detail and color accuracy in both fashion and beauty shots is vital. I used to shoot chrome or pro color neg, mostly 67 or 45. I now shoot digital, mostly 1Ds, sometimes Leaf. My images often run across a two-page spread, as big as 16x20. I'm still getting hired, so I can only assume that means digital is finally "here".
As for digital sensors and dynamic range, you must not have much experience with actual pro digital gear. High-end digital capture has as much dynamic range as traditional analog capture. And both have more dynamic range than any reflective print can display. So, since 99% of all images are intended for print, that extra dynamic range is just wasted, or used as a cushion for artistic changes.
And I don't take wedding photos either. Check out my site. The content was shot on everything from a point'n'shoot T4 to 67 chrome to 45 color neg, to 22mp digital capture. Each tool has a job, and increasingly, film's job is to waste money.